There has arisen a need to couple multiple cellular base stations with a single antenna assembly. Such base station coupling is termed co-siting. Co-siting cellular base stations provides for economies of space as well as cost. The need to co-site has arisen due to the proliferation of portable wireless communications device usage and the competing cellular phone technologies (e.g., TDMA, GSM, AMPS, CDMA).
Terrestrial based portable wireless communications device communications require a network of base stations acting as middlemen. Base stations send and receive signals between portable wireless communications devices and wireless or wireline switching centers. These base stations form cells of coverage. Base stations have a limited coverage area. Thus, a network of base stations is required to provide coverage to a large area. Each base station requires a large antenna assembly to pick-up and transmit signals to and from portable wireless communications devices.
Base stations were initially tied to an antenna assembly on a one-to-one basis depending on the flavor of the cellular system (e.g., TDMA, GSM, AMPS, CDMA). The antenna specifications were matched to the base station specifications in order to provide optimum RF performance. However, the proliferation of cellular phone usage and cellular phone technologies would require a corresponding increase in the number of base station and antenna assemblies under a one-to-one correspondence scenario. Due to the large and typically unappealing visual impact of antenna assemblies, it is desirable to minimize the number of antenna assemblies. The benefits of antenna sharing include staying within the space limitations on a particular tower assembly, the elimination of the need for labor and materials associated with adding a new antenna to a tower, the maintenance costs associated with an antenna, among others.
From a technical standpoint it is possible to “share” an antenna assembly among multiple base stations even if each base station is using a different technology. Thus, multiple base stations can be co-sited with a single antenna assembly thereby reducing the need for additional unsightly antenna assemblies.
The problem with sharing antenna assemblies among multiple disparate base station systems is that each base station uses a different set of specifications with respect to the antenna/base station interface. Thus, additional measures must be taken to provide the proper signal characteristics to each base station.
Currently, the signal gain level is adjusted in the master base station to match the expected signal gain level of a slave base station. The master base station is the base station that is directly coupled to the antenna assembly. Slave base stations receive their signals via an antenna sharing component in the master base station after the signal gain level has been adjusted. Adjusting the gain, however, has effects on the quality of the signal and often results in less than optimum RF performance.
What is needed is an apparatus for dynamically adjusting the gain to achieve optimal performance with respect to both signal strength and signal quality.